Core B exists to meet all of the cell culture and molecular biological needs of the COBRE Principal Investigators who are not routinely utilizing these methods in their own laboratories. This will ensure that each Investigator uses cellular and molecular regent that have been extensively characterized by the Core. The specific cell types and vectors are listed below. Core B will provide pluripotent E14 cerebral cortical- derived stem cells, neuron-restricted E14 spinal cord-derived stem cells, as well as genetically modified stem cells (see below) to all investigators as needed. Core B will construct required recombinant retroviruses, produce and titer the needed viral supernatants and infect any stem cell as required. A list of the cDNAs that are either in the retroviral vector or are presently being constructed is detailed below. These genetically modified cells will then be given to the COBRE Principal Investigators for their respective in vitro and/or in vivo assays. Core B will provide all recombinant adenoviral vectors that are needed by the COBRE Principal Investigators. Core B will enrich by fluorescence activated cell sorting (FACS) any stem cell populations expressing specific transgenes as required by the COBRE Principal Investigators. This Core will enable the Projects that use this Core to receive identical cells and vectors and will facilitate interaction between the respective Principal Investigators. It is expected that such interactions will make the COBRE Investigators more productive.